Osteosarcoma (OS) in dogs is biologically aggressive, with high metastatic potential and poor prognosis, closely resembling the human disease. In contrast, feline OS shows far lower metastatic rates, suggesting species-specific molecular mechanisms. Members of the ERM protein family—ezrin, radixin, and moesin—play critical roles in linking the actin cytoskeleton to the cell membrane and have been associated with tumor invasiveness and metastatic competence.
This study analyzed ezrin and moesin protein expression in osteosarcoma samples from 16 dogs and 8 cats using immunohistochemistry and western blot techniques. Overall, feline tumors demonstrated higher total moesin expression compared to canine tumors. However, a different pattern emerged when examining the active, phosphorylated forms of these proteins.
Dogs exhibited a notably higher abundance of phosphorylated ezrin (Tyr353) and activated moesin, forms that are strongly implicated in metastasis. Although phospho-ezrin Thr567 levels were elevated in feline OS, the crucial finding was the membranous localization of active ezrin in canine tumors, indicating stronger engagement of metastasis-associated signaling pathways.
Significant differences in immunohistochemical scoring for ezrin and pan-phospho-ERM proteins further support species divergence. These molecular contrasts may help explain why canine OS behaves more aggressively than its feline counterpart. The authors emphasize the need for additional research to determine how these phosphorylation patterns contribute to metastasis, prognosis, and therapeutic targets in both species.
Together, the findings provide valuable insight into the biology of osteosarcoma across species and highlight the importance of ERM protein activation as a potential driver of clinical outcomes.
Source: Hlavaty, J., Wolfesberger, B., Rütgen, B., et al. (2017). Ezrin and moesin expression in canine and feline osteosarcoma. Histology and Histopathology. Published August 1, 2017.
